1 / 5

2º AcousMed meeting 20-24 November 2010 Palma de Mallorca, Baleares, Spain

ACOUSMED Task 3:Harmonization and optimisation of the acoustic methodology Subtask 3.1: Target strength equations for anchovy and sardine. 2º AcousMed meeting 20-24 November 2010 Palma de Mallorca, Baleares, Spain. WP objectives. To decide a common protocol for analysis.

sachi
Download Presentation

2º AcousMed meeting 20-24 November 2010 Palma de Mallorca, Baleares, Spain

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ACOUSMEDTask 3:Harmonization and optimisation of the acoustic methodologySubtask 3.1: Target strength equations for anchovy and sardine. 2º AcousMed meeting 20-24 November 2010 Palma de Mallorca, Baleares, Spain

  2. WP objectives • To decide a common protocol for analysis. • Literature review of existing TS equations (Mediterranean and elsewhere) concerning sardine and anchovy. • To apply different TS equations in past acoustic data from each area and comparisons of the resulting abundant estimates will be made. • To estimate in situ TS equations for each target species, sardine and anchovy (2002-2006).

  3. Common protocol for analysis I • Monospecificnighthauls (80%) or with discrete modes on TS and TL. • Echoview or Movies software. • TS data from the haul sampled depth area. • Acoustic parameters for single targets as in WGACEGG 08: • Pulse length: 0.5 ms • Min. thr: -60 dB • Min.-Max echolength: [0.8 – 1.8] • Max phase deviation: to be adjusted, between 4 to 8 usually. • Export all available data from Echoview, single targets, fish tracks • Single target and fish track analysis (Echoview default values), Split beam method 2.

  4. Common protocol for analysis II • Filtering based on Tortuosity. To ensure that tracks were derived from a single individual and not multiple fish in close proximity, any track with a tortuosity value greater than 1.2 was excluded from analysis. • Bin range TS : 0.1 db • Bin range TL: 0.5 cm Two regressions can be conducted for each data set: • best-fit, and • a slope forced to 20 (Foote, 1979). • Apply both and use a t-test (α=0.05) to test whether slopes of the best-fit regressions are significantly different from 20. • Regression fit will be evaluated based on least squares • Use modal TL per haul to work and mean TL for equation • Similar approach to TS

  5. Re-analysis past surveys to check biomass differences • Biomass estimates based on: • The TS already applied • Sardine: -72.6, Anchovy: -71.2 • Sardine: -70.51, Anchovy: -75.3 • For 1 year: • Adriatic: North Adriatic • Spanish: Tramontana • GOL: entire area • Sicily: entire area • HCMR: entire area

More Related